When I turn before the end of the row, do I start knitting the previous stitches as outlined in the next row? Do I just knit or purl them accordingly and then go on to the next row? What in the pattern is this accomplishing?

I like to understand what the stitch I am doing is producing, and how that fits into the pattern as a whole. I would be most grateful for any help, or illumination on that point.

Welcome to Knitting Help!
You have it right. When you turn before the end of the row, start knitting the previous stitches as outlined in the instructions for "next row". The pattern wants you to follow exactly as written, row 1, turn, and you're on row 2. The reason for these short rows is shaping. You're adding extra rows in one place in this pattern in order to shape the head.
Hope you'll stick around with comments, questions and help for others too.